The present invention relates to methods for producing integrated circuit devices and more specifically to a selective sidewall diffusion process using doped spin on glass (SOG).
Known methods for diffusing impurities into planar semiconductor materials involve a masking operation followed by an implant operation in which n-type and p-type impurities are implanted into a planar substrate, typically silicon.
No known method exists for diffusing impurities into the sidewalls of depressions or raised portions of semiconductor materials. Implanting does not work well for sidewall diffusion because the implanting process is highly directional. The surface to be implanted must be oriented perpendicular to the direction from which the implanting is performed. During the implanting process, it is not feasible to rotate the semiconductor material in many directions to expose the various surfaces of the material to implanting. Surrounding surface structures may shadow adjacent structures, making side wall implantation impossible.
Furthermore, if a high energy implant is used to introduce the same dopant species to the same depth in the silicon, two detrimental effects will occur. First, the dopant would be introduced into the surface region of the silicon. Second, the implant would cause crystal lattice defects in the silicon.
Therefore, it would be desirable to provide a process for forming diffusing impurities into the sidewalls of depressions or raised portions of semiconductor materials.